A national day is a day on which celebrations mark the statehood or nationhood of a state or its people. It may be the date of independence, of becoming a republic, of becoming a federation, or a significant date for a patron saint or a ruler (such as a birthday, accession, or removal). The national day is often an official public holiday. Many countries have more than one national day. Denmark and the United Kingdom are the only countries without a national day. Denmark has what is not a public holiday but an unofficial celebration called Constitution Day. National days emerged with the age of nationalism, with most appearing during the 19th and 20th centuries. National day may also be known as Independence Day, Liberation Day, or Republic Day, depending on the nation, and its history.

[{{legend|#008000|Independence-related national day}} {{legend|#2BED2B|Unification/revolution-related national day}} {{legend|red|Other reasons for national day}} {{legend|#7F7F7F|No official national day|undefined | upload.wikimedia.org/wikipedia/commons/a/a7/National///Days///map///5///July///2024.png]

List of national days

Nations that are not broadly recognized sovereign states are shown in pink. Defunct states are highlighted in light grey. For nations that are dependent on, or part of, a sovereign state (such as federal states, autonomous regions, or colonies), the name of the sovereign state is shown in parentheses. Days that are not fixed to the Gregorian calendar are sorted by their occurrences.